United States Court of Appeals 

for the Federal Circuit 

__________________________ 

DURAMED PHARMACEUTICALS, INC. 

(NOW KNOWN AS TEVA WOMEN’S HEALTH, INC.), 

Plaintiff-Appellant, 

v. 

PADDOCK LABORATORIES, INC., 

Defendant-Appellee. 

__________________________ 

2010-1419 

__________________________ 

Appeal from the United States District Court for the 

Southern District of New York in Case No. 09-CV-1905, 

Senior Judge Leonard B. Sand. 

____________________________ 

Decided: July 21, 2011 

____________________________ 

CHARANJIT BRAHMA, Kirkland & Ellis, LLP, of Washington, DC, argued for plaintiff-appellant. With him on 

the brief were COREY J. MANLEY and J. JOHN LEE; and 

ALEXANDER F. MACKINNON, of Los Angeles, California. Of 

counsel was ROBERT G. KRUPKA, of Los Angeles, California. 

EDGAR H. HAUG, Frommer Lawrence & Haug, LLP, of 

New York, New York, argued for defendant-appellee. 

With him on the brief was DAVID A. ZWALLY. 
DURAMED PHARMA v. PADDOCK LABS 2

__________________________ 

Before LOURIE, GAJARSA, and DYK, Circuit Judges. 

LOURIE, Circuit Judge. 

Duramed Pharmaceuticals, Inc. (“Duramed”) appeals 

from the decision of the United States District Court for 

the Southern District of New York granting summary 

judgment of noninfringement to Paddock Laboratories, 

Inc. (“Paddock”). Duramed Pharms., Inc. v. Paddock 

Labs., Inc., 715 F. Supp. 2d 552 (S.D.N.Y. 2010). Because 

the district court did not err in holding that prosecution 

history estoppel bars Duramed’s allegations of infringement under the doctrine of equivalents, we affirm. 

BACKGROUND

Duramed owns U.S. Patent 5,908,638 (“’638 patent”), 

which claims conjugated estrogen pharmaceutical compositions for use in hormone replacement therapies. The 

claimed conjugated estrogens are extremely water sensitive and thus highly susceptible to moisture degradation 

during storage. See ’638 patent col.6 ll.46-56. Accordingly, Duramed developed a formulation for conjugated 

estrogens that includes a moisture barrier coating 

(“MBC”) to inhibit the absorption of moisture and reduce 

storage-related degradation. See id. col.6 ll.36-45. 

Duramed filed a patent application on its formulation 

on July 26, 1995. Original independent claim 1 recited a 

conjugated estrogen pharmaceutical composition “coated 

with a moisture barrier coating.” J.A. 254. Original 

dependent claim 7 limited “said moisture barrier coating” 

to one that “comprises ethylcellulose.” J.A. 255. The 

examiner rejected both claims as obvious, but during an 

interview advised that he would allow the application if 

Duramed amended claim 1 to include, inter alia, the 
3 DURAMED PHARMA v. PADDOCK LABS

limitations of claim 7. In a response received December 3, 

1998, Duramed amended claim 1 to recite pharmaceutical 

compositions with “a moisture barrier coating comprising 

ethylcellulose.” J.A. 304. Claim 1 of the issued ’638 

patent, the patent’s only independent claim, accordingly 

reads as follows: 

1. A pharmaceutical composition in a solid, unit 

dosage form capable of oral administration for the 

hormonal treatment of peri-menopausal, menopausal and post-menopausal disorders in a 

woman comprising: 

conjugated estrogens coated onto one or more organic excipients forming a powdered conjugated 

estrogen composition where said composition is 

substantially free of inorganic excipients and further comprises about 30-70% gel-forming organic 

excipient and about 30-70% non-gel forming organic excipient by weight and having less than 

about 2.5% free water by weight and greater than 

2.5% total water wherein said solid unit dosage 

form is coated with a moisture barrier coating 

comprising ethylcellulose. 

’638 patent claim 1 (emphasis added). 

In March 2009, Duramed filed suit against Paddock 

under 35 U.S.C. § 271(e)(2), alleging infringement of the 

’638 patent based on Paddock’s Abbreviated New Drug 

Application (“ANDA”) for a generic version of Duramed’s 

hormone replacement therapy product, Cenestin®. 

Duramed alleged infringement of claims 1, 4, and 6-8 

under the doctrine of equivalents, because Paddock’s 

proposed generic product uses a polyvinyl alcohol (“PVA”) 

MBC, marketed as Opadry AMB. Paddock moved for 

summary judgment of noninfringement, arguing that 

Duramed was barred by amendment-based prosecution 
DURAMED PHARMA v. PADDOCK LABS 4

history estoppel from alleging that PVA met the “moisture 

barrier coating comprising ethylcellulose” limitation of 

the asserted claims. 

In its motion for summary judgment, Paddock relied 

on several pre-amendment references, including an international patent application filed by Colorcon pursuant to 

the Patent Cooperation Treaty (“the Colorcon PCT”). The 

Colorcon PCT, published on January 25, 1996, discloses 

formulations of PVA-based MBCs, including Opadry 

AMB, but also, in a section entitled “Description of the 

Prior Art,” notes several technical drawbacks of using 

PVA as an MBC. Paddock also relied on (1) U.S. Patent 

3,935,326 (“the Groppenbächer patent”), which issued in 

1976 and discloses the use of PVA in moisture-tight 

tablets; (2) an article in the December 1995 issue of 

“Manufacturing Chemist” that tests PVA MBCs and 

concludes that Opadry AMB is a highly effective moisture 

barrier formulation; (3) three scientific articles on PVA 

MBCs authored for distribution at scientific conferences 

in May 1995, May 1998, and November 1998; and (4) 

invoices indicating sales of Opadry AMB by Colorcon 

before September 1996. 

The district court granted Paddock’s motion for summary judgment of noninfringement, holding that prosecution history estoppel barred Duramed’s infringement 

allegations. Duramed, 715 F. Supp. 2d at 555-56. The 

district court first held that Duramed’s amendment 

adding the ethylcellulose limitation was substantially 

related to patentability and narrowed the scope of the 

asserted claims, thus triggering the presumption under 

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 344 

F.3d 1359, 1366-67 (Fed. Cir. 2003) (en banc) (“Festo IX”), 

that Duramed had surrendered all territory between the 

original and amended claim scope. Duramed, 715 F. 

Supp. 2d at 559-60. 
5 DURAMED PHARMA v. PADDOCK LABS

The district court then held that Duramed had failed 

to rebut the Festo presumption based on an argument of, 

inter alia, the unforeseeability of the use of PVA as an 

MBC in a pharmaceutical formulation. Id. at 560. 

Rather, the court held that PVA MBCs were foreseeable 

at the time of Duramed’s narrowing amendment based on 

the Colorcon PCT’s description of PVA as “a moisture 

barrier coating for pharmaceutical tablets and the like” 

and its disclosure of the Opadry AMB formulation used in 

Paddock’s proposed generic product. Id. at 560-61. The 

court noted that several other facts reinforced this decision: (1) the pre-September 1996 invoices for the sale of 

Opadry AMB; and (2) the Groppenbächer patent, which 

teaches coating tablets with PVA to ensure “‘moisture 

tight[ness]’ and ‘insolub[ility] in the gastrointestinal 

tract.’”1 Id. at 561-62. Finally, the court rejected 

Duramed’s argument that the Colorcon PCT’s disclosure 

of PVA MBCs’ technical drawbacks raised serious questions about PVA’s effectiveness as an MBC, concluding 

that “even if the effectiveness of PVA was unknown in 

1998, that would not mean that PVA MBCs were unforeseeable.” Id. at 563. 

Duramed timely appealed to this court. We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1). 

DISCUSSION

We review a district court’s grant of summary judgment de novo, reapplying the same standard applied by 

 1 The district court did not consider Paddock’s remaining pre-1998 articles based on Duramed’s claim that 

a bench trial would be necessary to determine if the 1995 

“Manufacturing Chemist” article was publicly available in 

a university library and if the conference articles were 

actually distributed to the attendees. Id. at 561 n.8. The 

court concluded that these articles were not necessary to 

establish foreseeability. Id.
DURAMED PHARMA v. PADDOCK LABS 6

the district court. Iovate Health Scis., Inc. v. BioEngineered Supplements & Nutrition, Inc., 586 F.3d 1376, 

1380 (Fed. Cir. 2009). Summary judgment is appropriate 

if there are no genuine issues of material fact and the 

moving party is entitled to judgment as a matter of law. 

Fed. R. Civ. P. 56(c). 

Under the doctrine of the equivalents, “a product or 

process that does not literally infringe . . . the express 

terms of a patent claim may nonetheless be found to 

infringe if there is ‘equivalence’ between the elements of 

the accused product or process and the claimed elements 

of the patented invention.” Warner-Jenkinson Co. v. 

Hilton Davis Chem. Co., 520 U.S. 17, 21 (1997) (citing 

Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 

605, 609 (1950)). However, the doctrine of prosecution 

history estoppel prevents a patent owner from recapturing through the doctrine of equivalents subject matter 

surrendered to acquire the patent. See Festo Corp. v. 

Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 734 

(2002) (“Festo VIII”). 

Because during prosecution Duramed narrowed the 

scope of the ’638 patent’s claims in response to a prior art 

rejection, a presumption of prosecution history estoppel 

applies. See Festo IX, 344 F.3d at 1366-67. Nonetheless, 

Duramed may rebut that presumption by showing, inter

alia, the “alleged equivalent would have been ‘unforeseeable at the time of the amendment and thus beyond a fair 

interpretation of what was surrendered.’” Id. at 1369 

(quoting Festo VIII, 535 U.S. at 738). “[A]n alternative is 

foreseeable if it is disclosed in the pertinent prior art in 

the field of the invention. In other words, an alternative 

is foreseeable if it is known in the field of the invention as 

reflected in the claim scope before amendment.” Festo 

Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 493 F.3d 

1368, 1379 (Fed. Cir. 2007) (“Festo X”). Foreseeability is a 
7 DURAMED PHARMA v. PADDOCK LABS

question of law based on underlying issues of fact. Id. at 

1375. 

On appeal, Duramed argues that the district court 

applied the wrong legal test for foreseeability and thus 

held that any mention of an alleged equivalent in the 

prior art makes that equivalent foreseeable as a matter of 

law. But, according to Duramed, an equivalent is not 

foreseeable if it was not understood by one of ordinary 

skill in the art to be suitable for use in the invention as 

originally claimed. And, in this case, Duramed asserts, 

the relevant art did not disclose either PVA or Opadry 

AMB as suitable MBCs for moisture-sensitive pharmaceutical compounds, like conjugated estrogens. 

Paddock responds that the district court applied the 

correct foreseeability standard, which requires only that 

PVA be foreseeable as an MBC for pharmaceutical applications at the time of Duramed’s narrowing amendment. 

In this case, according to Paddock, the Colorcon PCT 

alone renders PVA MBCs foreseeable, but this conclusion 

is bolstered by Colorcon’s commercialization of Opadry 

AMB, the Groppenbächer patent, and the other references 

not considered by the district court. 

We agree with Paddock that Duramed failed to rebut 

the presumption of prosecution history estoppel based on 

unforeseeability. We first note that, to the extent that 

Duramed argues that foreseeability requires that PVA 

must have been known as an MBC for use with conjugated estrogens, we have previously rejected such a restrictive definition of the field of invention. See Schwarz 

Pharma, Inc. v. Paddock Labs., Inc., 504 F.3d 1371, 1377 

(Fed. Cir. 2007). As we spelled out in Schwarz, when the 

language of both original and issued claims begins with 

the words “[a] pharmaceutical composition,” that language defines the field of the invention for purposes of 
DURAMED PHARMA v. PADDOCK LABS 8

determining foreseeability. Id. Accordingly, PVA MBCs 

need only to have been known in the field of pharmaceutical compositions as of the time of Duramed’s narrowing 

amendment, see Festo X, 493 F.3d at 1379, which we hold 

that the Colorcon PCT establishes as a matter of law. 

The Colorcon PCT discloses PVA MBCs for use with 

pharmaceutical compositions: “A dry powder moisture 

barrier coating composition is made to form a moisture 

barrier film coating for pharmaceutical tablets and the 

like, which comprises polyvinyl alcohol . . . .” J.A. 4466. 

In the “Description of the Prior Art” the PCT states that 

“[t]he use of the polymer polyvinyl alcohol, PVA, as a 

moisture barrier coating has been previously suggested,” 

but it also notes two drawbacks of PVA MBCs: stickiness 

and plasticizer compatibility. Id. Specifically, the Colorcon PCT states: 

[P]ractical usage [of PVA] has been inhibited by 

the stickiness of grades of the polymer which have 

a fast enough rate of going into solution in water 

to make a dispersion to render them economical to 

use in making the coating. A further problem 

with the use of PVA is in identifying or selecting a 

plasticizer which does not compromise the moisture barrier properties of the final coating. 

Id. 

The Colorcon PCT then, in the “Summary of the Invention,” discloses preferred PVA grades and identifies a 

plasticizer that does not compromise PVA’s properties as 

a moisture barrier. The application states that 

“[e]xcellent moisture barrier properties are obtained when 

hot water soluble grades of PVA are used in the inventive 

coating,” and that “[a] preferred grade of PVA for use in 

the inventive coating is a grade in the medium range . . . 

because the step of heating the water of the liquid coating 
9 DURAMED PHARMA v. PADDOCK LABS

dispersion may not be necessary, while still maintaining 

excellent moisture barrier properties in the inventive 

coating.” J.A. 4468-69. The Colorcon PCT next discloses 

that soya lecithin “surprisingly, and unexpectedly, acts as 

a plasticizer by locking moisture in the coating so the 

coating stays flexible and not brittle,” and thus soya 

lecithin as a plasticizer “does not compromise the moisture barrier properties of the overall coating.” J.A. 4469. 

Finally, the Colorcon PCT lists a number of PVA MBC 

formulations, including Opadry AMB. Accordingly, the 

Colorcon PCT discloses PVA MBCs, including Opadry 

AMB, in the field of pharmaceutical compositions, rendering such PVA MBCs “known in the field of the invention,” 

and thus foreseeable. Festo X, 493 F.3d at 1379. 

Duramed argues that the Colorcon PCT’s disclosure 

fails to establish that PVA-based Opadry AMB was suitable as an MBC because it provides only conclusory 

statements that the inventors had solved the technical 

drawbacks of PVA MBCs and lacks any data on the 

stability of the pharmaceutical compounds coated with 

Opadry AMB. We disagree; foreseeability does not require such precise evidence of suitability. See Honeywell 

Int’l, Inc. v. Hamilton Sundstrand Corp., 523 F.3d 1304, 

1312-13 (Fed. Cir. 2008). And even if the PCT disclosure 

indicates that PVA is less than ideal in some pharmaceutical uses as an MBC, it is still disclosed to be useful as 

such, and that renders it foreseeable for purposes of 

prosecution history estoppel. Foreseeability does not 

require flawless perfection to create an estoppel. 

In rejecting a foreseeability rebuttal in Glaxo Wellcome, Inc. v. Impax Laboratories, Inc., 356 F.3d 1348 (Fed. 

Cir. 2004), we held that “the record abundantly disclosed 

[the alleged equivalent’s] use as a release agent at the 

relevant time,” SmithKline Beecham Corp. v. Excel 

Pharms., Inc., 356 F.3d 1357, 1365 (Fed. Cir. 2004) (de-
DURAMED PHARMA v. PADDOCK LABS 10

scribing Glaxo, 356 F.3d at 1355). Our holding relied on 

statements from several references disclosing the alleged 

equivalent’s use as an extended-release agent in drug 

formulations; it did not rely on test data showing the 

alleged equivalent’s precise characteristics or suitability 

as an extended-release agent, and thus did not rely on the 

type of evidence Duramed demands in this case. See

Glaxo 356 F.3d at 1355. Rather, the Colorcon PCT discloses the use of PVA as MBCs in the field of pharmaceutical compounds prior to December 3, 1998, rendering 

such PVA MBCs foreseeable at the time of Duramed’s 

narrowing amendment.2 

 2 Although not necessary to our decision, we note 

that the 1995 “Manufacturing Chemist” article also 

supports a finding of foreseeability in the case. Like the 

Colorcon PCT, the “Manufacturing Chemist” article 

discloses PVA MBCs for use in pharmaceutical applications, and it discloses tests on the performance of PVAbased coatings with moisture-sensitive drugs. The tests 

compared PVA MBCs with hydroxypropyl-methylcellulose 

MBCs coating tablets of aspirin or erythromycin ethylsuccinate stored for twelve weeks under high relative humidity. The data reveal that “the PVA formulation gives 

much superior moisture protection under humid storage 

conditions.” J.A. 4497. The article concludes that “[t]he 

results presented here have shown a highly effective 

moisture barrier formulation [based on the water soluble 

polymer PVA, designated Opadry AMB] has been developed.” J.A. 4498. The district court did not rely on this 

article based on Duramed’s claim that a bench trial would 

be necessary to determine if the article was publicly 

available. Duramed, 715 F. Supp. 2d at 561 n.8. We 

disagree that there is a genuine issue of material fact on 

the public availability of an article published in a scientific journal three years before Duramed’s amendment. 

See, e.g., In re Lister, 583 F.3d 1307, 1312 (Fed. Cir. 2009). 
11 DURAMED PHARMA v. PADDOCK LABS

CONCLUSION

For the foregoing reasons, we affirm the district 

court’s grant of summary judgment of noninfringement. 

AFFIRMED